JP6918069B2 - Power receiving device - Google Patents

Description

One aspect of the disclosed invention relates to a power receiving device and a power feeding system.

With the widespread use of various electronic devices, a wide variety of products are being shipped to the market. In recent years, portable electronic devices such as mobile phones and digital video cameras have become remarkably widespread. In addition, electric propulsion vehicles such as electric vehicles that obtain power based on electric power are also appearing on the market as products.

For mobile phones, digital video cameras, or electric propulsion mobiles, power storage devices (power storage devices)
It also has a built-in battery (also called a storage battery). At present, most of the power supply of the power storage device is directly contacted with a household AC power source which is a power supply means. Further, in a configuration that does not include a power storage device or a configuration that does not use the power supplied to the power storage device, the current situation is that power is directly supplied from a household AC power supply via wiring or the like for operation.

On the other hand, research and development on a method of supplying power to a power storage device or a load by non-contact is also progressing, and as a typical method, an electromagnetic coupling method (also referred to as an electromagnetic induction method) (Patent Document 1).
(See), radio wave method (also referred to as microwave method), magnetic field resonance method (also referred to as resonance method) (see Patent Document 2 and Patent Document 3).

As shown in Patent Document 2, in the magnetic field resonance type non-contact power feeding technology, each of a device on the power receiving side (hereinafter referred to as a power receiving device) and a device on the power supplying side (hereinafter referred to as a power transmission device). However, it has a resonance coil. Further, the power receiving device and the power transmitting device are each provided with an electromagnetic induction coil. Power supply from the power supply in the power transmission device to the resonance coil, and
Power is supplied from the resonance coil to the load in the power receiving device via the electromagnetic induction coil.

The resonance coil of the power transmitting device and the resonance coil of the power receiving device are set so that their resonance frequencies (LC resonance) match so that the magnetic field resonance phenomenon appears at a specific frequency.

By causing the resonance coil of the power transmission device and the resonance coil of the power receiving device to face each other and causing a magnetic field resonance phenomenon, efficient power transmission can be realized even when the resonance coils are separated from each other (see Non-Patent Document 1). ).

Japanese Unexamined Patent Publication No. 2011-223716 Japanese Unexamined Patent Publication No. 2011-297999 Japanese Unexamined Patent Publication No. 2011-166883

"Wireless Power Transfer 2010 All About Contactless Charging and Wireless Power Transfer" Nikkei Electronics, March 2010, pp. 66-81

However, as charging of the power storage device progresses, there arises a problem that the charging current to the power storage device decreases and the resistance value of the power receiving device increases.

An increase in the resistance value of the power receiving device has a great influence on the coupling between the resonance coils that perform power transmission due to the magnetic field resonance phenomenon, and as a result, the power transmission efficiency may decrease. For example, as the resistance value of the power receiving device increases, the LC resonance of the resonance coil cannot be maintained, and the magnetic field resonance phenomenon that has been exhibited does not occur.

Further, in a non-contact power feeding system, if communication is performed between the power transmission device and the power receiving device at the same time as power feeding by using the electromagnetic induction coil and the resonance coil, it is preferable because the information of each of the power transmitting device and the power receiving device can be exchanged. For example, when the charging of the power storage device is completed, the information that the power storage device is fully charged is transmitted from the power receiving device to the power transmission device, and the power transmission from the power transmitting device to the power receiving device is stopped. This makes it possible to prevent overcharging of the power storage device.

However, when the resistance value of the power receiving device increases, the degree of modulation of the modulated signal transmitted between the power receiving device and the power transmitting device is affected. When the degree of modulation of the modulated signal is affected, the modulated signal received by one or both of the power transmitting device and the power receiving device cannot be read, and as a result, the stability of communication between the power transmitting device and the power receiving device is ensured. There is a fear that it will not be possible.

In view of the above, one of the problems of the disclosed uniform state of the invention is to obtain a power supply system capable of suppressing a decrease in power transmission efficiency in power supply to the power storage device.

Further, one of the problems of the disclosed invention is to obtain a power supply system capable of ensuring the stability of communication performed at the same time as power supply.

The uniform aspects of the disclosed invention are an antenna portion having a resonance coil, a capacitor, an electromagnetic induction coil, a rectifier circuit, a power storage device, a current detection circuit that detects a current value flowing through the power storage device, and the like. A charging circuit unit having a voltage detection circuit for detecting a voltage value applied to a power storage device, and a charging circuit unit.
A control circuit that generates a selection signal based on the detected current value and voltage value, a plurality of switches that are turned on or off by the selection signal, and electrically connected to each of the plurality of switches. The present invention relates to a power receiving device including a communication control unit having a passive element and a passive element.

The homogeneity of the disclosed invention is a power transmission device having an AC power supply, a first electromagnetic induction coil, a first resonance coil, and a first capacitor, a second resonance coil, and a second. An antenna unit having a capacitor, a second electromagnetic induction coil, a rectifying circuit, a power storage device, a current detection circuit that detects a current value flowing through the power storage device, and a voltage that detects a voltage value applied to the power storage device. A charging circuit unit having a detection circuit, a control circuit that generates a selection signal based on the detected current value and voltage value, a plurality of switches that are turned on or off by the selection signal, and a plurality of switches. The present invention relates to a power supply system comprising a communication control unit having a passive element electrically connected to each of the switches, and a power receiving device having the passive element.

As the charging of the power storage device progresses, the resistance value of the power storage device increases, and the resistance value of the entire power receiving device increases. This reduces the power transmission efficiency. However, the optimum passive element provided in the communication control unit is connected based on the current value flowing through the power storage device and the voltage value applied to the power storage device. As a result, it is possible to suppress the influence on the coupling between the resonance coils that perform power transmission due to the magnetic field resonance phenomenon, and to maintain the best power transmission efficiency between the power transmission device and the power receiving device at all times.

Further, when the charging of the power storage device progresses and the resistance value of the power storage device and the power receiving device increases, the degree of modulation of the modulated signal used for communication in the communication between the power transmitting device and the power receiving device performed at the same time as the power supply is increased. Change. When the degree of modulation of the modulated signal changes and the signal becomes unreadable, communication between the power transmitting device and the power receiving device becomes impossible. Therefore, as the charging of the power storage device progresses and the resistance value of the power receiving device increases, the instability of communication increases. However, by connecting the optimum passive element provided in the communication control unit based on the current value flowing through the power storage device and the voltage value applied to the power storage device, the degree of modulation of the modulated signal between the power transmission device and the power reception device is high. Can always maintain the best condition. Thereby, it is possible to stabilize the communication between the power transmitting device and the power receiving device.

In the uniformity of the disclosed invention, the passive element is one of a capacitor, a coil, and a resistor.

In the uniform aspect of the disclosed invention, the plurality of switches are characterized by being transistors, respectively.

According to the uniformity of the disclosed invention, it is possible to obtain a power supply system capable of suppressing a decrease in power transmission efficiency in power supply to the power storage device.

Further, according to the uniform state of the disclosed invention, it is possible to obtain a power supply system capable of ensuring the stability of communication performed at the same time as power supply.

Circuit diagram of the power supply system. A flowchart showing the operation of the power supply system. Circuit diagram of the power supply system. The figure explaining the voltage amplitude. The figure which shows the relationship between the frequency and the power transmission efficiency when a load is changed. The figure which shows the relationship between the resistance value of a load and the communication success probability. The figure which shows the relationship between the resistance value of a load and the power transmission efficiency.

Hereinafter, embodiments of the invention disclosed in the present specification will be described with reference to the drawings. However, the invention disclosed in the present specification can be carried out in many different modes, and its form and details are variously changed without departing from the spirit and scope of the invention disclosed in the present specification. What can be done is easily understood by those skilled in the art. Therefore, the interpretation is not limited to the description of the present embodiment. In the drawings shown below, the same parts or parts having similar functions are designated by the same reference numerals, and the repeated description thereof will be omitted.

The positions, sizes, ranges, etc. of each configuration shown in the drawings and the like may not represent the actual positions, sizes, ranges, etc., in order to make the explanation easier to understand. Therefore, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings and the like.

It should be noted that the ordinal numbers such as "first", "second", and "third" in the present specification and the like are added to avoid confusion of the components, and are not limited numerically. do.

<Structure of power supply system>
FIG. 1 is a circuit diagram of a power supply system incorporating a wireless communication function. The power supply system shown in FIG. 1 includes a power transmission device 100 and a power reception device 110.

In the power feeding system shown in FIG. 1, the electromagnetic wave generated by the power transmitting device 100 is amplitude-modulated, and the electromagnetic wave (modulated signal) to which the amplitude modulation is applied is used to perform wireless communication between the power transmitting device 100 and the power receiving device 110. The modulated signal transmitted from the power transmitting device 100 to the power receiving device 110 is used as a transmission signal. Further, the modulation signal transmitted from the power receiving device 110 to the power transmitting device 100 is used as a reply signal.

The power transmission device 100 includes an AC power supply 101 that generates AC power, a first electromagnetic induction coil 102, and the like.
It has a first resonance coil 103 and a first capacitor 104.

Further, the power receiving device 110 has an antenna portion 114 having a second capacitor 111, a second resonance coil 112, and a second electromagnetic induction coil 113. Further, the power receiving device 110 is
It has a charging circuit unit 130 having a rectifier circuit 115, a smoothing circuit 116, a current detection circuit 117, a voltage detection circuit 118, and a power storage device 119. Further, the power receiving device 110 has a communication control unit 120 having a control circuit 121, a signal receiving circuit 122, and an adjusting circuit 126. The adjusting circuit 126 includes a transistor 124_1 which is a first switch, a capacitor 125_1 which is a first passive element, a transistor 124_2 which is a second switch, a coil 125_2 which is a second passive element, and an n-1 switch. A transistor 124_n-
It has a resistor 125_n-1, which is a first n-1 passive element, a transistor 124_n, which is an nth switch, and a resistor 125_n, which is an nth passive element.

Note that n is a natural number of 2 or more. Further, in the present embodiment, a capacitor 125_1 is used as the first passive element, a coil 125_2 is used as the second passive element, a resistor 125_n-1 is used as the n-1 passive element, and a resistor 125_n is used as the nth passive element. , Each of the first passive element to the nth passive element may use any one of a capacitor, a coil, and a resistor.
The first passive element, the second passive element, the n-1 passive element, and the nth passive element shown in FIG. 1 are
It is just an example. The details of what kind of passive element is used as each of the first passive element to the nth passive element and the method of determining the number of passive elements (the number of n) will be described later.

The AC power supply 101 is a power supply that generates AC power having a predetermined frequency. The first terminal and the second terminal of the AC power supply 101 are electrically connected to one terminal and the other terminal of the first electromagnetic induction coil 102, respectively.

Here, "electrically connected" includes not only direct electrical connection but also indirect electrical connection. Therefore, the first terminal and the second terminal of the AC power supply 101 are directly electrically connected to one terminal and the other terminal of the first electromagnetic induction coil 102, respectively, and the first terminal of the AC power supply 101 The terminal 1 and the second terminal also include being electrically connected to one terminal and the other terminal of the first electromagnetic induction coil 102, respectively, via another electrode or wiring.

One terminal and the other terminal of the first resonance coil 103 are electrically connected to one terminal and the other terminal of the first capacitor 104, respectively.

The power supply from the AC power supply 101 to the first resonance coil 103 is performed by using the electromagnetic coupling method via the first electromagnetic induction coil 102.

The first electromagnetic induction coil 102 of the power transmission device 100 and the second electromagnetic induction coil 113 of the power receiving device 110 described later are, for example, coils wound in about one loop, and the first resonance coil 103 of the power transmission device 100. The second resonance coil 112 of the power receiving device 110, which will be described later, is, for example, a coil wound in about several loops.

The first resonance coil 103 of the power transmission device 100 and the second resonance coil 112 of the power receiving device 110, which will be described later, are coils with both ends open. The first resonance coil 103 and the second resonance coil 112 have a capacitor due to stray capacitance. As a result, the first resonance coil 103 and the second resonance coil 112 become an LC resonance circuit. The capacitor is not limited to the stray capacitance method, and an LC resonance circuit may be realized by electrically connecting a capacitor at both ends of the coil.

The first resonance coil 103 of the power transmission device 100 and the second resonance coil 112 of the power receiving device 110
Is set so that the respective resonance frequencies (LC resonance) match so that the magnetic field resonance phenomenon appears at a specific frequency.

The first resonance coil 103 of the power transmission device 100 and the second resonance coil 112 of the power receiving device 110 face each other to cause a magnetic field resonance phenomenon, so that efficient power can be obtained even when the distance between the resonance coils is large. Transmission can be realized.

In the power transmission technology using a coil, there is k × Q as an index parameter indicating high transmission efficiency (k is a coupling coefficient, Q is a Q value of a resonance coil). The coupling coefficient k is a coefficient indicating the degree of coupling between the resonance coil on the power feeding side and the resonance coil on the power receiving side. The Q value is a value representing the sharpness of the resonance peak of the resonance circuit. In the magnetic field resonance type power feeding technology, in order to realize high transmission efficiency, the resonance coil 103 and the co-second resonance coil 112 are set to have a very high Q value (for example, Q is 100). It is preferable to use a larger value (k × Q is larger than 1).

In the power receiving device 110, one terminal and the other terminal of the second resonance coil 112 are the second terminals.
It is electrically connected to one terminal and the other terminal of the capacitor 111 of the above.

In FIG. 1, the power transmission device 100 includes a first electromagnetic induction coil 102, a first resonance coil 103, a first capacitor 104 (referred to as a power transmission element), and a power reception device 110.
The second electromagnetic induction coil 113, the second resonance coil 112, and the second capacitor 111 (
It has a power receiving element), but is not limited to this. As the power transmitting element and the power receiving element, a magnetic field type element using a helical antenna or an electric field type element using a meander line antenna may be used, respectively.

One terminal of the second electromagnetic induction coil 113 is electrically connected to the first terminal of the rectifier circuit 115 and the first terminal of the communication control unit 120. The other terminal of the second electromagnetic induction coil 113 is electrically connected to the second terminal of the rectifier circuit 115 and the second terminal of the communication control unit 120.

The rectifier circuit 115 functions as an AC-DC converter (AC-DC converter) that converts AC power into DC power. As the rectifier circuit 115 of the present embodiment, for example, a rectifier bridge composed of four diodes is used. The first terminal of the rectifier circuit 115 is electrically connected to one terminal of the second electromagnetic induction coil 113 and the first terminal of the communication control unit 120. The second terminal of the rectifier circuit 115 is electrically connected to the other terminal of the second electromagnetic induction coil 113 and the second terminal of the communication control unit 120. The third terminal of the rectifier circuit 115 is electrically connected to the first terminal of the smoothing circuit 116 and the first terminal of the current detection circuit 117. The fourth terminal of the rectifier circuit 115 is grounded.

The smoothing circuit 116 has a function of smoothing the DC power by storing and discharging the DC power output from the rectifier circuit 115. As the smoothing circuit 116, a capacitor is used in this embodiment. The first terminal of the smoothing circuit 116 is electrically connected to the third terminal of the rectifier circuit 115 and the first terminal of the current detection circuit 117. The second terminal of the smoothing circuit 116 is grounded. The smoothing circuit 116 may be configured not to be provided if it is not necessary.

The current detection circuit 117 is a circuit that detects the current value flowing through the power storage device 119. The first terminal of the current detection circuit 117 is the third terminal of the rectifier circuit 115 and the first terminal of the smoothing circuit 116.
It is electrically connected to the terminal of. The second terminal of the current detection circuit 117 is the voltage detection circuit 1
It is electrically connected to the first terminal of 18 and the positive electrode of the power storage device 119. The third terminal of the current detection circuit 117 is electrically connected to the third terminal of the communication control unit 120, and information (signal) of the current value flowing through the power storage device 119 is input to the communication control unit 120.

The voltage detection circuit 118 is a circuit that detects the voltage value applied to the power storage device 119. The first terminal of the voltage detection circuit 118 is electrically connected to the second terminal of the current detection circuit 117 and the positive electrode of the power storage device 119. The second terminal of the voltage detection circuit 118 is electrically connected to the negative electrode of the power storage device 119 and is grounded. The third terminal of the voltage detection circuit 118 is electrically connected to the fourth terminal of the communication control unit 120, and the information (signal) of the voltage value applied to the power storage device 119 is input to the communication control unit 120.

The positive electrode of the power storage device 119 is electrically connected to the second terminal of the current detection circuit 117 and the first terminal of the voltage detection circuit 118. The negative electrode of the power storage device 119 is electrically connected to the second terminal of the voltage detection circuit 118 and is grounded.

As described above, the communication control unit 120 includes a control circuit 121, a signal reception circuit 122, and an adjustment circuit 126.

The control circuit 121 has a function of processing and analyzing a transmission signal transmitted from the power transmission device 100, and a function of processing and analyzing the transmission signal.
It has a function of generating a reply signal having information of the power receiving device 110. Further control circuit 121
Is input with information (signal) of the current value flowing through the power storage device 119 detected by the current detection circuit 117 and information (signal) of the voltage value applied to the power storage device 119 detected by the voltage detection circuit 118. It has a function of generating a selection signal for controlling the on state and the off state of the first switch to the nth switch based on the current value information and the voltage value information. Based on the selection signal, the first switch to the nth switch is turned on or off, and is connected to the passive element connected to the first switch to the nth switch, which is turned on. The passive element that is being used functions electrically.

The first terminal of the control circuit 121 is the first terminal of the communication control unit 120, and the transistor 1
One of the source or drain of 24_1, one of the source or drain of transistor 124_2, one of the source or drain of transistor 124_n-1, and transistor 12
It is electrically connected to either the source or drain of 4_n. The second terminal of the control circuit 121 is the second terminal of the communication control unit 120, and is the first terminal of the signal receiving circuit 122, one terminal of the capacitor 125_1, one terminal of the coil 125_2, and the resistor 125_n-1. It is electrically connected to one terminal and one terminal of the resistor 125_n. Control circuit 12
The third terminal of 1 is the third terminal of the communication control unit 120, and is electrically connected to the third terminal of the current detection circuit 117. The fourth terminal of the control circuit 121 is the fourth terminal of the communication control unit 120, and is electrically connected to the third terminal of the voltage detection circuit 118. The fifth terminal of the control circuit 121 is electrically connected to the gate of the transistor 124_1, the gate of the transistor 124_2, the gate of the transistor 124_n-1, and the gate of the transistor 124_n. The sixth terminal of the control circuit 121 is electrically connected to the second terminal of the signal receiving circuit 122.

The signal receiving circuit 122, also called a decoder, shapes the received transmission signal so that the control circuit 121 can analyze the signal. Further, the signal receiving circuit 122 has a function of removing noise and the like. The first terminal of the signal receiving circuit 122 is the second terminal of the control circuit 121, one terminal of the capacitor 125_1, one terminal of the coil 125_2, one terminal of the resistor 125_n-1, and one terminal of the resistor 125_n. Is electrically connected to. Signal receiving circuit 122
The second terminal is electrically connected to the sixth terminal of the control circuit 121.

One of the source or drain of the transistor 124_1, which is the first switch, is the first terminal of the control circuit 121, one of the source or drain of the transistor 124_2, one of the source or drain of the transistor 124_n-1, and the source of the transistor 124_n. Or it is electrically connected to one of the drains. The other of the source or drain of the transistor 124_1 is electrically connected to the other terminal of the capacitor 125_1. The gate of transistor 124_1 is electrically connected to the fifth terminal of the control circuit 121, the gate of transistor 124_2, the gate of transistor 124_n-1, and the gate of transistor 124_n.

One terminal of the capacitor 125_1, which is the first passive element, is a second terminal of the control circuit 121, a first terminal of the signal receiving circuit 122, one terminal of the coil 125_2, and a resistor 125_n.
It is electrically connected to one terminal of -1 and one terminal of a resistor 125_n. The other terminal of the capacitor 125_1 is electrically connected to the other of the source or drain of the transistor 124_1.

One of the source or drain of the transistor 124_2, which is the second switch, is the first terminal of the control circuit 121, one of the source or drain of the transistor 124_1, one of the source or drain of the transistor 124_n-1, and the source of the transistor 124_n. Or it is electrically connected to one of the drains. The other of the source or drain of transistor 124_2 is electrically connected to the other terminal of coil 125_2. The gate of transistor 124_2 is electrically connected to the fifth terminal of the control circuit 121, the gate of transistor 124_1, the gate of transistor 124_n-1, and the gate of transistor 124_n.

One terminal of the coil 125_2, which is the second passive element, is a second terminal of the control circuit 121.
First terminal of signal receiving circuit 122, one terminal of capacitor 125_1, resistor 125_n
It is electrically connected to one terminal of -1 and one terminal of a resistor 125_n. The other terminal of coil 125_2 is electrically connected to the other of the source or drain of transistor 124_2.

One of the source and drain of transistor 124_n-1, which is the n-1th switch,
It is electrically connected to the first terminal of the control circuit 121, one of the source or drain of the transistor 124_1, one of the source or drain of the transistor 124_2, and one of the source or drain of the transistor 124_n. The other of the source or drain of transistor 124_n-1 is electrically connected to the other terminal of resistor 125_n-1. The gate of transistor 124_n-1 is the fifth terminal of the control circuit 121, transistor 12
It is electrically connected to the gate of 4-1, the gate of transistor 124_2, and the gate of transistor 124_n.

One terminal of the resistor 125_n-1, which is the passive element of the n-1, is a second terminal of the control circuit 121, a first terminal of the signal receiving circuit 122, one terminal of the capacitor 125_1, and a coil 1.
It is electrically connected to one terminal of 25_2 and one terminal of a resistor 125_n. The other terminal of resistor 125_n-1 is electrically connected to the other of the source or drain of transistor 124_n-1.

One of the source or drain of the transistor 124_n, which is the nth switch, is the first terminal of the control circuit 121, one of the source or drain of the transistor 124_1, one of the source or drain of the transistor 124_2, and the source of the transistor 124_n-1. Or it is electrically connected to one of the drains. The other of the source or drain of transistor 124_n is electrically connected to the other terminal of resistor 125_n. Transistor 1
The gate of 24_n-1 is electrically connected to the fifth terminal of the control circuit 121, the gate of the transistor 124_1, the gate of the transistor 124_2, and the gate of the transistor 124_n.

One terminal of the resistor 125_n, which is the nth passive element, is a second terminal of the control circuit 121, a first terminal of the signal receiving circuit 122, one terminal of the capacitor 125_1, and a coil 125_2.
It is electrically connected to one terminal and one terminal of the resistor 125_n-1. Resistance 1
The other terminal of 25_n is electrically connected to the other of the source or drain of transistor 124_n.

As described above, each of the first passive element to the nth passive element may use any one of a capacitor, a coil, and a resistor, and the first passive element and the second passive element shown in FIG. 1 may be used. Nth nth
The passive element of -1 and the passive element of the nth are merely examples. Charging proceeds depending on which passive element is used from the first passive element to the nth passive element provided in the adjustment circuit 126, that is, which passive element the switch connected to is turned on. Based on the information (signal) of the resistance value of the power storage device 119 of the power receiving device 110, which increases with time, the power transmission efficiency between the power transmitting device 100 and the power receiving device 110 and the degree of modulation of the modulated signal are determined to be the best. The resistance value information (signal) of the power storage device 119 is calculated from the current value information (signal) flowing through the power storage device 119 and the voltage value information (signal) applied to the power storage device 119. Based on the resistance value information (signal) of the power storage device 119, the control circuit 121 determines which switch is turned on or off and which passive element is used at the same time as the charging of the power storage device 119 progresses. decide.

As described above, the power transmission efficiency between the power transmission device and the power receiving device can always be maintained in the best state. Therefore, it is possible to obtain a power supply system capable of suppressing a decrease in power transmission efficiency in power supply to the power storage device.

Further, the degree of modulation of the modulated signal used for communication between the power transmitting device and the power receiving device can always be maintained in the best state. Therefore, it is possible to obtain a power supply system capable of ensuring the stability of communication performed at the same time as power supply.

<Flowchart showing operation>
FIG. 2 is a flowchart showing the operation of the power supply system of the present embodiment.

First, the power transmission device 100 transmits AC power and transmits a transmission signal (S101). The AC power and the transmission signal are transmitted from the first electromagnetic induction coil 102 to the first resonance coil 103 by electromagnetic coupling. The first resonance coil 103 and the first capacitor 104, and the second resonance coil 112 and the second capacitor 111 are adjusted so that their respective resonance frequencies (LC resonances) are the same. As a result, a magnetic field resonance phenomenon occurs at a specific frequency between the first resonance coil 103 and the second resonance coil 112, and the power receiving device 110 can receive AC power and receive a transmission signal (S102). ..

The received AC power is input to the charging circuit unit 130, and the received transmission signal is input to the communication control unit 120 (S103).

In the charging circuit unit 130, the input AC power is rectified by the rectifier circuit 115 and converted from AC power to DC power (S104).

When the obtained DC power is input to the power storage device 119, the current value flowing through the power storage device 119 is detected by the current detection circuit 117, and the voltage value applied to the power storage device 119 is detected by the voltage detection circuit 118 (S105). The obtained current value and voltage value information (signals) are input to the control circuit 121 of the communication control unit 120, respectively. Further, the power storage device 119 is charged by the DC power (S106).

Further, after step S103, the transmission signal input to the communication control unit 120 is the signal reception circuit 1.
It is input to 22 (S111). The signal receiving circuit 122 shapes the transmitted signal so that the control circuit 121 can analyze the transmitted signal.

The transmission signal shaped by the signal receiving circuit 122 is input to the control circuit 121, and the control circuit 12
It is analyzed in 1 (S112).

The current value and voltage value information (signal) detected in step S105 is input to the control circuit 121. Based on the input information (signal), the control circuit 121 is the first passive element to the nth.
It is determined which of the passive elements of the above is used to obtain the best power transmission efficiency between the power transmitting device 100 and the power receiving device 110 and the best modulation degree of the modulated signal (transmission signal and reply signal) (S).
113).

Based on the determination in step S113, the control circuit 121 generates a selection signal for determining which switch is to be turned on or off, and is connected to the first passive element to the nth passive element by the selection signal. The on state and the off state of the switch being switched are switched (S11).
4). As a result, the power receiving device 110 has the best power transmission efficiency and the best modulation degree.
The resistance value of is changed.

In step S114, the reply signal having the highest modulation degree is transmitted from the power receiving device 110 to the power transmitting device 100 (S115).

The power transmission device 100 that has received the reply signal transmits a new transmission signal to the power reception device 110 based on the received reply signal.

As described above, in the power supply system of the present embodiment, as the charging of the power storage device 119 progresses,
Even if the resistance value of the power receiving device 110 increases, it is possible to always transmit AC power with the best transmission efficiency and to communicate with a modulated signal having the best modulation degree.

As described above, according to the present embodiment, the decrease in the power transmission efficiency in the power supply to the power storage device is suppressed, and the decrease in the power transmission efficiency is suppressed.
It is possible to ensure the stability of communication performed at the same time as power supply.

In this embodiment, the result of the measurement performed by the uniform power feeding system of the disclosed invention will be described.

<Structure of power supply system>
FIG. 3 shows the configuration of the power supply system used in this embodiment. The power supply system shown in FIG. 3 has a power transmission device 100 and a power reception device 140. Since the power transmission device 100 shown in FIG. 3 and the power transmission device 100 shown in FIG. 1 are the same, the description of the first embodiment is incorporated.

The power receiving device 140 shown in FIG. 3 includes an antenna unit 114, a load unit 142, and a communication control unit 141.
have. The load unit 142 includes a rectifier circuit 115, a smoothing circuit 116, and a current detection circuit 11.
7. It has a voltage detection circuit 118 and a load 129. The communication control unit 141 has a resistor 131,
It has a switch 132, a diode 133, and a control circuit 135. Further, the first terminal of the switch 132 and the control circuit 135 are connected by wiring 134.

Since the antenna portion 114, the rectifier circuit 115, the smoothing circuit 116, the current detection circuit 117, and the voltage detection circuit 118 of the power receiving device 140 are the same as those in the first embodiment, the description thereof will be described in the first embodiment.
Incorporate the explanation of.

The load 129 of the power receiving device 140 is provided in place of the power storage device 119 of FIG. Further, the resistor 131 of the power receiving device 140 is provided in place of the adjustment circuit 126 of FIG. In this embodiment, the degree of modulation of the modulated signal is adjusted by changing the resistance value of the resistor 131 instead of switching the on state and the off state of the transistors 124_1 to 124_n in the adjusting circuit 126. For comparison, measurements were also made for a resistor 131 in which the resistance value was not changed and the degree of modulation of the modulated signal was not adjusted. Under the above conditions, the relationship between power transmission efficiency and communication success probability was investigated.

The current value flowing through the load 129 is detected by the current detection circuit 117. Also load 129
The voltage value applied to is detected by the voltage detection circuit 118. The detected current value and voltage value are input to the control circuit 135. The first terminal of the resistor 131 is the communication control unit 141.
The first terminal of the rectifier circuit 115, which is one terminal of the second electromagnetic induction coil 113.
Is electrically connected to the terminal of the diode and the input terminal of the diode 133. Second of resistor 131
Terminal is electrically connected to the second terminal of the switch 132.

The switch 132 controls the electrical connection and disconnection of the second terminal and the third terminal based on the signal from the control circuit 135 input to the first terminal. The first terminal of the switch 132 is electrically connected to the second terminal of the control circuit 135 via the wiring 134. The potential of the wiring 134 is defined as the potential Vc (details will be described later). The second terminal of the switch 132 is electrically connected to the second terminal of the resistor 131. The third terminal of the switch 132 is the second terminal of the communication control unit 141, and is electrically connected to the other terminal of the second electromagnetic induction coil 113 and the second terminal of the rectifier circuit 115. ..

The input terminal of the diode 133 is electrically connected to the first terminal of the resistor 131. The output terminal of the diode 133 is electrically connected to the first terminal of the control circuit 135.

The control circuit 135 has a function of processing and analyzing a transmission signal transmitted from the power transmission device 100, and a function of processing and analyzing the transmission signal.
It has a function of generating a reply signal having information of the power receiving device 140, a function of controlling the resistance value of the resistor 131, and a function of controlling the potential Vc applied to the first terminal of the switch 132 via the wiring 134. ..

The high level potential or low level potential output from the second terminal of the control circuit 135 is applied to the first terminal of the switch 132 by using the wiring 134. As a result, the control circuit 135
When the potential output from the second terminal of the switch 132 is a high level potential, the second terminal and the third terminal of the switch 132 are electrically connected, and the potential output from the second terminal of the control circuit 135. When is a low level potential, the second and third terminals of the switch 132 are not electrically connected.

The first terminal of the control circuit 135 is electrically connected to the output terminal of the diode 133. The second terminal of the control circuit 135 is electrically connected to the first terminal of the switch 132 via the wiring 134. Information (signal) of the current value from the current detection circuit 117 is input to the third terminal of the control circuit 135. The voltage detection circuit 11 is connected to the fourth terminal of the control circuit 135.
Information (signal) of the voltage value from 8 is input.

<Power transmission>
FIG. 5 shows the relationship between the frequency and the power transmission efficiency when the resistance value of the load 129 is changed to 50Ω, 100Ω, 1000Ω, and 5000Ω. FIG. 5 shows, for example, a load of 129 at 13.56 MHz, which is used as the frequency of a wireless communication system using RFID technology.
It has been shown that the higher the resistance value of, the lower the power transmission efficiency.

In FIG. 7, the load 12 is used when the resistance value of the resistor 131 is changed and when it is not changed.
The relationship between the resistance value of 9 and the power transmission efficiency is shown. In FIG. 7, the frequency was measured at 13.56 MHz. When changing the resistance value of the resistor 131, the resistance value of the resistor 131 was changed by feeding back the current value flowing through the load 129 and the voltage value applied to the load 129 based on the flowchart of FIG.

As shown in FIG. 7, when the resistance value of the resistor 131 is changed, the power transmission efficiency is 90.
It is almost constant at% or more. However, when the resistance value of the resistor 131 is not changed,
As the resistance value of the load 129 increases, the power transmission efficiency decreases, and in particular, the resistance value of the load 129 sharply decreases near 100Ω. When the resistance value of the resistor 131 is not changed in this way, the power transmission efficiency decreases as the resistance value of the load 129 increases.

From this example, it was clarified that the decrease in power transmission efficiency can be suppressed in the power feeding system in which the resistance value of the resistor 131 is changed and the modulation degree of the modulated signal is adjusted.

<Communication>
FIG. 4 is a diagram showing the voltage amplitude of the potential Vc of the wiring 134 and the voltage amplitude of the potential V0 of the AC power supply 101 when the resistance value of the resistance 131 is changed. In FIGS. 4 (A) and 4 (C), the vertical axis represents the potential Vc and the horizontal axis represents time. Further, in FIGS. 4B and 4D, the vertical axis represents the potential V0 and the horizontal axis represents time. 4 (A) and 4 (B) show the voltage amplitude of the potential Vc and the voltage amplitude of the potential V0 when the communication is unsuccessful. The voltage amplitude of the potential Vc shown in FIGS. 4 (A) and 4 (C) is
Both are the same. When the potential Vc changes from a high level potential to a low level potential,
The voltage amplitude of the potential V0 becomes smaller. On the contrary, when the potential Vc changes from the low level potential to the high level potential, the voltage amplitude of the potential V0 becomes large.

In this example, the high level potential was set to 3.3 V and the low level potential was set to 0 V.

The threshold potential Vt shown in FIGS. 4 (B) and 4 (D) is a reference potential for determining whether the potential is a high level potential or a low level potential. In this embodiment, when the maximum value of the voltage amplitude is larger than the threshold potential Vt, it is regarded as a high level potential, and when the maximum value of the voltage amplitude is smaller than the threshold potential Vt, it is regarded as a low level potential. ing. In this embodiment, the value of the threshold potential Vt is determined in consideration of the voltage amplitude of the noise at the potential V0.

As shown in FIG. 4B, at the time of successful communication, the potential V0 corresponding to the change of the potential Vc from the high level potential to the low level potential or the change of the potential Vc from the low level potential to the high level potential. There is a sufficient difference in voltage amplitude. When there is a sufficient difference in the voltage amplitude of the potential V0 as described above, the modulation signal can be exchanged.

On the other hand, as shown in FIG. 4 (D), even if the potential Vc changes from a high level potential to a low level potential or the potential Vc changes from a low level potential to a high level potential, the potential is not successful when communication is unsuccessful. There is no sufficient difference in the voltage amplitude of V0. That is, the voltage amplitude of the potential V0 shown in FIG. 4 (D) is always regarded as a high level potential, and no signal can be transmitted at this voltage amplitude. Therefore, when the potential V0 shown in FIG. 4D can be obtained, communication is impossible.

Further, FIG. 6 shows the relationship between the resistance value of the load 129 and the communication success probability when the resistance value of the resistor 131 is changed and when it is not changed. Also in FIG. 6, the frequency is 13.56M.
Measured in Hz.

In this embodiment, a modulation signal (transmission signal) is transmitted from the power transmission device 100 to the power reception device 140.
The power receiving device 140 receives the transmitted modulation signal, and the power receiving device 140 returns the modulation signal (reply signal) to the received modulation signal to the power transmission device 100 once, and the operation is performed 50 times. The communication success probability in FIG. 6 is the ratio of the number of successful communications out of the 50 operations.

As shown in FIG. 6, when the resistance value of the resistor 131 is changed, the communication success probability is 90.
It is almost constant at% or more. However, when the resistance value of the resistor 131 is not changed,
As the resistance value of load 129 increases, the communication success probability decreases, and the resistance value of load 129 decreases to 30.
When it is Ω, the communication success probability becomes 0%. That is, when the resistance value of the resistor 131 is not changed and the resistance value of the load 129 is 30Ω or more, the power transmission device 100 and the power receiving device 1
Communication between 40 is impossible.

As described above, according to this embodiment, it has been clarified that even when the load 129 is increased, the decrease in power transmission efficiency can be suppressed by changing the resistance value of the resistor 131.

Further, according to this embodiment, it has been clarified that even when the load 129 is increased, the stability of communication can be ensured by changing the resistance value of the resistor 131 and adjusting the modulation degree of the modulated signal.

100 Transmission device 101 AC power supply 102 First electromagnetic induction coil 103 First resonance coil 104 First capacitor 110 Power receiving device 111 Second capacitor 112 Second resonance coil 113 Second electromagnetic induction coil 114 Antenna section 115 rectification Circuit 116 Smoothing circuit 117 Current detection circuit 118 Voltage detection circuit 119 Power storage device 120 Communication control unit 121 Control circuit 122 Signal reception circuit 124_1 Transistor 124_2 Transistor 124_n-1 Transistor 124_n Transistor 125_1 Capacitor 125_1 Coil 125_n-1 Resistance 125_n Resistance 126 Adjustment circuit 129 Load 130 Charging circuit 131 Resistance 132 Switch 133 Diode 134 Wiring 135 Control circuit 140 Power receiving device 141 Communication control 142 Load

Claims (3)

An antenna unit having an electromagnetic induction coil and a resonance coil,
A charging circuit unit to which AC power received by the antenna unit is input, and a charging circuit unit.
It has a communication control unit provided between the antenna unit and the charging circuit unit.
The charging circuit unit
A rectifier circuit that converts AC power into DC power,
A power storage device that is charged by the converted DC power, and
A current detection circuit that detects the value of the current flowing through the power storage device, and
It has a voltage detection circuit for detecting a voltage value applied to the power storage device, and has a voltage detection circuit.
The communication control unit
It has an adjustment circuit and a control circuit,
The adjustment circuit
With multiple passive elements
It has a switch connected in series with the passive element.
The plurality of passive elements are electrically connected in parallel to the electromagnetic induction coil.
The control circuit turns the switch on or off so as to maximize the charging efficiency based on the current value information detected by the current detection circuit and the voltage value information detected by the voltage detection circuit. Power receiving device to control. In claim 1,
The passive element is a power receiving device that is any one of a capacitor, a coil, and a resistor. In claim 1 or 2,
The plurality of switches are power receiving devices, each of which is a transistor.

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